In the United States, 17% of overall national health expenditures are linked to cardiovascular diseases. $50 billion are spent annually on end stage renal disease (ESRD). Cardiovascular disease and the treatment of ESRD often require synthetic vascular grafts. Almost 1.4 million vascular grafts are needed every year in the US alone. However, the success rate of current synthetic vascular grafts in many vascular sites is low. For example, arteriovenous Teflon grafts, the most prevalent graft in the market for hemodialysis, has a failure rate of 50% in one year.
The most common causes of vascular graft failure are thrombosis and intimal hyperplasia (excessive cell growth). The mismatch of mechanical properties of the currently used rigid vascular graft materials (e.g., ePTFE and Dacron) and elastic native blood vessels contributes to turbulence and repeated damage to the native blood vessel under the cyclical, pulsatile blood flow, and suboptimal blood compatibility of current vascular graft materials induces thrombosis. Additionally, in healthy native blood vessels, a single layer of endothelial cells forms an inner lining called the endothelium that can suppress smooth muscle cell proliferation or intimal hyperplasia, which is another major cause of vascular graft failures. Another serious complication of vascular grafts is infection. Current biomaterials generally elicit a cascade of reactions (foreign body reaction, or FBR) orchestrated by macrophages that result in a scar layer that separate the material from the rest of the body, creating heavens for bacterial infections.
These complications can be addressed by development of synthetic vascular grafts that have mechanical properties tunable to match those of the native blood vessels; sufficient strength to withstand suture; be stable in the body in the long term, and promote complete healing of a healthy endothelial cell layer on the luminal surface of the synthetic vascular grafts. Even though synthetic graft materials having some of these characteristics have been developed, complete healing of endothelium in synthetic vascular grafts has not been demonstrated to date. Thus, a need exists for a synthetic vascular prosthesis that has physical properties matching those of a native blood vessel and at the same time promotes endothelial healing.